Immersion-cooled inductors in DC-to-DC converters and methods of operating thereof

Abstract

Described herein are DC-DC converters having various immersion-cooling features enabling high-power applications, such as cross-charging electric vehicles. For example, the inductor of a DC-DC converter may be formed using metal and insulator sheets stacked and wound into an inductor coil assembly. The metal sheet comprises grooves, extending parallel to the coil axis and forming coil fluid pathways through this assembly thereby providing immersion cooling to the inductor. An inductor-cooling liquid may be pumped through these fluid pathways while being in direct contact with the metal sheet, at least around the grooves. In some examples, these grooves are distributed along the entire length of the metal sheet. Multiple inductors may be used to enable operations of multiple converter units, e.g., operating out of phase. These inductors may be fluidically interconnectors and have the same cooling features.

The invention claimed is: 
     
       1. A DC-DC converter comprising:
 a converter unit comprising a power electronic module and an inductor, wherein:
 the power electronic module comprises a switching sub-module and a diode sub-module, 
 the inductor comprises a metal sheet and an insulator sheet stacked and wound together into an inductor coil assembly, comprising a coil axis, and 
 the metal sheet comprises grooves, extending parallel to the coil axis and forming coil fluid pathways together with the insulator sheet and remaining portions of the metal sheet. 
 
 
     
     
       2. The DC-DC converter of  claim 1 , wherein:
 the metal sheet has a length, and 
 the grooves are evenly distributed along the length of the metal sheet. 
 
     
     
       3. The DC-DC converter of  claim 1 , wherein:
 the inductor comprises an inductor housing, sealably enclosing the inductor coil assembly and comprising a first inductor fluid connector and a second inductor fluid connector, and 
 the coil fluid pathways fluidically couple the first inductor fluid connector and the second inductor fluid connector. 
 
     
     
       4. The DC-DC converter of  claim 3 , wherein a combined cross-sectional area of the coil fluid pathways is equal or greater than an orifice area of each of the first inductor fluid connector and the second inductor fluid connector. 
     
     
       5. The DC-DC converter of  claim 3 , wherein a combined cross-sectional area of the coil fluid pathways is at least 50 square millimeters. 
     
     
       6. The DC-DC converter of  claim 3 , wherein the inductor further comprises a flow distribution plate positioned between the first inductor fluid connector and the inductor coil assembly or between the second inductor fluid connector and the inductor coil assembly. 
     
     
       7. The DC-DC converter of  claim 1 , wherein the metal sheet comprises at least 100 instances of the grooves. 
     
     
       8. The DC-DC converter of  claim 1 , wherein each of the grooves has a semicircular shape. 
     
     
       9. The DC-DC converter of  claim 1 , wherein each of the grooves has a height of 0.2-0.8 millimeters. 
     
     
       10. The DC-DC converter of  claim 1 , wherein each of the coil fluid pathways is formed together by a corresponding one of the grooves and a portion of the insulator sheet adhered to an adjacent layer of the metal sheet. 
     
     
       11. The DC-DC converter of  claim 1 , wherein:
 the grooves further form additional coil fluid pathways such that each adjacent pair of the additional coil fluid pathways is separated by the metal sheet, formed into a corresponding one of the grooves, and 
 the additional coil fluid pathways have an elongated shape tapering away from the corresponding one of the grooves. 
 
     
     
       12. The DC-DC converter of  claim 1 , further comprising an additional converter unit, wherein:
 the additional converter unit comprising an additional inductor, 
 the additional inductor comprises an additional metal sheet and an additional insulator sheet stacked and wound into an additional inductor coil assembly, comprising an additional coil axis, 
 the additional metal sheet comprises additional grooves, extending parallel to the additional coil axis and forming additional coil fluid pathways together with the additional insulator sheet and remaining portions of the additional metal sheet, and 
 the additional inductor is fluidically coupled to the inductor. 
 
     
     
       13. The DC-DC converter of  claim 12 , wherein the converter unit and the additional converter unit are configured to operate out of phase. 
     
     
       14. The DC-DC converter of  claim 12 , further comprising a front plate, a first inductor-cooling coupler, a second inductor-cooling coupler, a first fluid connection, and a second fluid connection, wherein:
 the first fluid connection and the second fluid connection are positioned on the front plate, 
 the inductor comprises a first inductor fluid connector, a second inductor fluid connector, and a flow splitter, 
 the additional inductor comprises a first additional inductor fluid connector, a second additional inductor fluid connector, and an additional flow splitter, 
 the first inductor fluid connector is coupled to and configured to receive an inductor-cooling liquid from the first inductor-cooling coupler, 
 the flow splitter is coupled to the second additional inductor fluid connector by the first fluid connection and is configured to split the inductor-cooling liquid, received from the first inductor fluid connector, into a first portion, directed to the inductor coil assembly, and a second portion, directed to the first fluid connection, 
 the second inductor fluid connector is connected to the additional flow splitter by the second fluid connection, and 
 the additional flow splitter is configured to combine the first portion of the inductor-cooling liquid, received from the additional inductor coil assembly, and the second portion, received from the second fluid connection, into a combined fluid flow and direct the combined fluid flow to the first additional inductor fluid connector, coupled to the second inductor-cooling coupler. 
 
     
     
       15. The DC-DC converter of  claim 14 , wherein the first fluid connection and the second fluid connection are configured to maintain substantially same flow rates. 
     
     
       16. A method of operating a DC-DC converter, the method comprising:
 providing a DC-DC converter comprising a converter unit comprising a power electronic module and an inductor, wherein:
 the power electronic module comprises a switching sub-module and a diode sub-module, 
 the inductor comprises a metal sheet and an insulator sheet stacked and wound together into an inductor coil assembly, comprising a coil axis, and 
 the metal sheet comprises grooves, extending parallel to the coil axis and forming coil fluid pathways together with the insulator sheet and remaining portions of the metal sheet; and 
 
 flowing an inductor-cooling liquid through the coil fluid pathways while operating the DC-DC converter to boost an output voltage relative to an input voltage. 
 
     
     
       17. The method of  claim 16 , wherein the inductor-cooling liquid comes in direct contact with portions of the metal sheet forming the grooves. 
     
     
       18. The method of  claim 16 , wherein the DC-DC converter operates at a rate of at least 200 kW for at least a period of time. 
     
     
       19. The method of  claim 16 , further comprising:
 monitoring temperature of the inductor-cooling liquid upon exiting the inductor coil assembly; and 
 adjusting a volumetric flow rate of the inductor-cooling liquid through the inductor coil assembly based on the temperature of the inductor-cooling liquid upon exiting the inductor coil assembly. 
 
     
     
       20. The method of  claim 16 , further comprising:
 monitoring temperature of the inductor-cooling liquid upon exiting the inductor coil assembly; and 
 adjusting power output of the DC-DC converter based on the temperature of the inductor-cooling liquid upon exiting the inductor coil assembly.